End effectors are the last element of a kinematic chain of transport apparatuses, e.g. robots. They are used e.g. for gripping or holding objects.
In the production of chips, end effectors are typically used for holding substrates, such as wafers, in order to move the substrates between different process stations.
Suction apparatuses for end effectors for the production of microchips are known and typically have a suction groove or a suction cup, e.g. a sealing lip fastened to the end effector. By means of a channel in the end effector, negative pressure can be produced within the suction cup or the suction groove, said negative pressure being able to be used for picking up flat objects, such as substrates or wafers.
During suction through a groove, the substrate lies in most cases directly on the end effector. This prevents the substrate from moving after it has been picked up. However, this is possible only in the case of substrates having particularly planar and smooth surfaces. Curved substrates cannot be fixed to the end effector in this manner.
A suction cup can be used to also hold curved substrates because they do not lie directly against the end effector. However, small movements of the substrate are still possible which can reduce the precision of the placement of the substrate. Moreover, by virtue of the comparatively large volume in the suction cup, it is not possible for the substrate to be released rapidly. For example, the release action is assisted by flushing the line or switching to excess pressure. Furthermore, this type of suction frequently leads to adhesion of the substrates on the suction cup, thus making the release thereof more difficult.
Moreover, when fixing substrates by means of conventional suction grooves or seals, a suction force acts locally upon the location of the suction groove or the seal which frequently have a particularly small diameter for maximising the suction force. Particularly thin and fragile substrates can be damaged as a result.